Timed variable output pump

ABSTRACT

A pump having a piston of variable stroke driven by a pair of cooperating eccentrics both of which are adjustably carried by a single driven shaft. The shaft is provided with helical grooves within which ride followers for positioning of the eccentrics upon axial shaft movement. The outer eccentric functions as a cam to drive a follower and pump piston. The eccentricity of the outer eccentric may be varied by moving the outer eccentrics center progressively towards the axis of the shaft to adjust the stroke of the pump piston.

United States Patent Cuda 51 July 1 l, 1972 s41 TIMED VARIABLE OUTPUT PUMP 2,592,237 4/1952 Bradley....................................74/S7l [72] Inventor: Charles H. Cudl, 9405 NW. 9th Ave, Prim ry mnuner-Meyer Perlm Vancouver wash 98665 Assistant Examiner-Wesley S. Ratliff, Jr. 2 Aug 2 1970 Attorney-James D. GivnanJr.

[ pp 66,416 51 ABSTRACT A pump having a piston of variable stroke driven by a pair of [52] [1.8. CI. 74/57] R cooperating eccentrics both ofwhich are adjustably carried by [51] Int. 25/08 a single driven shaft. The shafi is provided with helical grooves [58] 55 i h hi h ri followers r p i i ning of the eccentrics upon axial shaft movement. The outer eccentric functions as a I 56] a cm cam to drive a follower and pump piston. The eccentricity of the outer eccentric may be varied by moving the outer eccen- UNlTED STATES PATENTS trics center progressively towards the axis of the shaft to adjust the stroke of the pump piston. 2,348,958 5/1944 Cello.......................................74/57l 1,956,447 4/1934 Laessker ..74/57 I 4 Claims, 8 Drawing Figures PATENTED JUL 1 I I972 SHEET 1 0f 2 L 0 5 225% f Jr a I mm u w H m Ilfllfrfl T a M 4| E CHARLES H CUDA INVENTOR.

AGENT PATENTEuJuL H 12. 2 3.675.498

SHEET 2 or 2 CHARLES H. GUDA I NV ENT OR.

BY AGENT TIMED VARIABLE OUTPUT PUMP BACKGROUND OF THE INVENTION The present invention relates to pumps and more particularly to adjustable eccentrics providing an adjustable cam surface for reciprocating a pump piston.

The present invention includes inner and outer cooperating eccentrics the combination of which, in itself, has been utilized in different arrangements including use with piston type pumps. In such uses the timing of the pump impulse is not critical. Upon adjustment of the cooperating eccentrics of prior art devices the point of maximum eccentricity of the outer eccentric will occur at different degrees of rotation which in ordinary pump operation is of no concern. In distinction, one form of the instant pump means provides a timed pump impulse as for instance in a fuel injection system with the timing not effected by the adjustment of the eccentricity of the driving cam surface. The present pumps impulse will occur in each instance upon the shaft of the pump passing through or other pre-determined point. The prior art arrangements, to the extent known, do not provide an adjustable cam surface usable in such a manner.

SUMMARY OF THE INVENTION The present invention is embodied within a driven shaft carrying inner and outer cooperating eccentrics with adjustment means therefor interacting between the shaft and the eccentrics to impart opposite, arcuate movement to the eccentrics. Such opposite movement of the eccentrics necessarily occurs at a different rate, in one form of the invention, for the purpose of retaining the center of the outer eccentric and hence maximum eccentricity thereof at 0 whereat a cam follower is located.

It is a primary object of the present invention to provide pump means embodying simultaneously adjustable eccentrics to vary the stroke of a cam follower and hence a piston of a pump reciprocably mounted within the pump housing. The impulse or pump output for each stroke of the pumps piston is timed to occur in a fixed relationship to the driving shaft of the pump throughout the adjustment range of the eccentrics. Importantly, as in the case ofa fuel injecting pump, the impulse is in a direct relationship to the speed of the pumps driven shaft regardless of the adjusted position of the eccentrics.

Another important object is the provision of helical adjustment means which arcuately moves the inner and the outer eccentrics in opposite directions. The maximum eccentricity of the outer eccentric is thereby variable to vary the stroke of a follower and its associated piston. In one of the embodiments shown the maximum eccentricity occurs at top dead center throughout all adjusted positions of the eccentrics. The maximum displacement of the cam follower resulting from the eccentrics occurs in fixed relationship to a point on the shafts periphery thus the pump impulse always occurs in a timed manner with the pump shaft.

A further object resides in adjustment means including helically extending grooves of unlike configuration wherein helical means function to impart rotational movement to the eccentrics with the inner eccentric moving about the axis of the driving shaft and the outer eccentric being positioned oppositely and simultaneously about said movable inner eccentric.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side elevational view of an embodiment of the present invention with fragments of the pump housing removed for purposes of illustration,

FIG. 2 is a side elevational view of the drive shaft removed from the pump structure of FIG. 1,

FIG. 3 is a sectional view taken along line 3-3 of FIG. 1 with the eccentrics positioned for maximum displacement of a cam follower,

FIGS. 4, 5 and 6 are views similar to FIG. 3 with the eccentrics oppositely in progressively increasing degrees for reduced displacement of the cam follower,

FIG. 7 is an enlarged detail view of a grooved fragment of the pumps drive shaft and taken downwardly along lines 7-7 of FIG. 2, and

FIG. 8 is a view similar to FIG. 2 showing a modified form of adjustment means.

DESCRIPTION OF PREFERRED EMBODIMENT In the continued reference to the drawings wherein applied reference numerals indicate parts similarly identified in the following specification, the reference numeral 10 indicates a driven shafi in engagement at one of its ends at 10A with a powering element 11. The shaft 10 is journalled as at 12 and is adapted for rectilinear movement therewithin while maintaining engagement with the source of power 11.

A shaft positioning assembly includes a control rod 13, a yoke 14 and a pivot support 15 for the yoke. Axially directed forces may be imparted to the rotating shaft 10 through a collar 16 having pins 16A engaged by the yoke 14. The collar may be the outer race of a bearing unit and hence isolated from shaft rotation yet capable of imparting fore and aft movement to the shaft.

With attention to FIGS. 3 through 6 the cooperating inner and outer eccentrics are shown at 17 and 18. Inner eccentric 17 includes an integral first collar 20 through which shaft 10 extends in a close sliding fit. Projecting inwardly from the collar 20 and integral therewith are helical means comprising a pin element 21 for reception within a spirally shaped slot or groove 22 (FIG. 2) in the shaft 10.

The outer eccentric at 18 defines an internal annular wall 23 disposed about the periphery of inner eccentric 17. Adjustable movement of eccentric 18 about inner eccentric 17 is achieved by a second collar at 24 carried by shaft 10 and having an integral arm 25 slidably engageable with a stub shaft 26 on eccentric 18. The collar 24, in similarity to the first described collar, includes additional helical means in the form of a pin element at 27 for reception within a spiral groove 28 formed in the shaft 10 (FIGS. 2 and 7). As seen in FIGS. 3 through 6, wherein arm 25 is shown in difierent adjusted positions, the outer eccentric I8 is rotated by means of the arm 25 bearing against the stub shaft 26 with the latter moving during eccentric adjustment progressively inwardly along the arm to the innermost portion as shown in FIG. 6. In FIG. 3 and parent FIG. 1 the eccentrics are shown adjusted for maximum throw a distance indicated at Y. The arcuate movement imparted to eccentric 18 is somewhat less than the arcuate travel of arm 25 by reason of the lost motion type coupling provided therebetween.

During adjustment of the eccentrics the center of eccentric 18, indicated at A, progressively descends towards the axis at 27 of shaft 10. The path of movement of the center A is within a vertical plane P containing the axis at 27 of shaft 10. Since center A of eccentric 18 remains at all times in the vertical plane P, maximum eccentricity, for any adjusted position of eccentrics 17-18, will remain at top center.

In FIGS. 4 through 6 the eccentrics have been oppositely positioned by axial shaft movement in equal increments from the FIG. 3 position. The relationship of axial shaft movement to rotational movement of eccentric 17 remains constant throughout all positioning of eccentric 17 while eccentric 18 during adjustment rotates in a varying relationship to axial shaft movement. To effect such movement one form of the invention includes the helical groove 28 of a non-constant spiral configuration as best viewed in FIG. 7 in comparison with the remaining spirally shaped groove 22 which is formed along a constant helical course.

Adjusted positions of the pin elements 21 and 27 for eccentries 17 and 18 respectively are indicated in FIG. 7 as follows;

Position 1 at P1 corresponds to FIG. 3,

Position 2 at P2 corresponds to FIG. 4,

Position 3 at P3 corresponds to FIG. 5, and

Position 4 at P4 corresponds to FIG. 6.

Axial movement of the shaft, as aforesaid, is accomplished by means of the shafi positioning assembly including the control rod 13.

An eccentric follower is indicated at 30 associated with the piston 31 in a pump housing H. Valves at 32 and 33 control the inflow and outflow of fluid into the pump cylinder 34 while a spring at 35 assures continuous contact of the follower with the contacting periphery of eccentric 18.

In operation the shaft positioning assembly upon fore and aft movement of rod 13, moves shaft with collars and 24 moving arcuately in opposite directions and at different rates. Throughout all adjusted positions of shaft, the center A of eccentric 18 remains in the vertical plane P with the stroke of the follower and pump piston being reduced as the center A of eccentric l8 approaches, during adjustment, the axis of shaft 10.

With the present pump means a timed impulse of fluid may be discharged into a fuel injection system with the quantity of the fluid pumped being variable. Obviously the rotational speed of shaft 10 may be varied to vary the rate of the fluid impulses.

In FIG. 8 l disclose a modified form of the invention wherein the arm at is of curved configuration. The stub shaft 26' is confined for adjustable movement within a slot of like curved configuration to effect the desired movement of the outer eccentric 18' about the shafi 10'. In this form of the invention the shaft 10 is provided with a pair of oppositely directed grooves similar to those earlier described but wherein both of said spiral grooves are of identical helical configuration to impart equal rotational movement to each of the pin carrying collars on the shaft 10. The curvature of arm 25' during initial adjustment from its position in FIG. 8, provides a greater degree of lost motion to compensate for undesired arcuate arm motion resulting from its associated helical groove being of curved configuration identical to groove 22 but, of course, oppositely directed.

For operation of the present pump in an environment where it is not necessary or desirable to retain the maximum eccentricity of the outer eccentric in a single vertical plane, as for instance in a hydraulic pump, the pair of helical grooves in shaft 10 may both be of a constant or identical helical configuration. Accordingly, the collars 20 and 24 carried by the shaft 10 and the arm 25 will rotate equally in opposite directions resulting in the center of eccentric 18 being moved (during adjustment) not within the vertical plane P but advancing in the direction of adjustment rotation of collar 24 but at a lesser rate of movement.

While I have shown various embodiments of the invention, it will be obvious to those skilled in the art that the invention may be embodied still otherwise without departing from the spirit and scope of the invention.

Having thus described the invention what is desired to be secured under a Letters Patent is:

1. Means for varying the stroke of a pump piston while retaining a fixed timed relationship between pump impulses and an imaginary point on a drive shaft powering said piston, said means comprising,

a powered shaft joumalled within the pump housing and adapted for rectilinear movement relative thereto,

means for imparting rectilinear positioning movement to said shaft,

an inner eccentric movably mounted on said shaft,

helical means carried by said shaft for imparting arcuate movement to said inner eccentric in a first direction upon axial displacement of said shaft,

an outer eccentric circumposed about said inner eccentric and having a circular peripheral surface for imparting reciprocal motion to the pump piston,

additional helical means carried by said shaft for imparting arcuate movement to said outer eccentric in a direction opposite to said first direction of the inner eccentric upon axial displacement of said shaft, and

means coupling said additional helical means to said outer eccentric and providing for lost motion therebetween during arcuate movement of the outer eccentric by said additional helical means with the center of said outer eccentric ad'ustably movin along a single plane containing the axis 0 the powered s aft with maximum eccentricity of the outer eccentric at all times occuring along said single plane and in a fixed coplanar relationship with the imaginary point on said powered shaft.

2. Means for varying the stroke of a pump piston as claimed in claim 1 wherein said helical means includes axially spaced curvilinear grooves formed in and directed oppositely about said shaft and follower pins disposed within said grooves.

3. Means for varying the stroke of a pump piston as claimed in claim 2 wherein the grooves in said shaft are of unlike curvature for imparting desired dissimilar arcuate movement in a simultaneous manner to both inner and outer eccentrics.

4. Means for varying the stroke of a pump piston as claimed in claim 2 wherein said grooves are of like curvature, said coupling means including an arm of curved configuration adapted to provide varying degrees of lost motion between said additional helical means and the outer eccentric during adjustment of the piston.

l l IF i 

1. Means for varying the stroke of a pump piston while retaining a fixed timed relationship between pump impulses and an imaginary point On a drive shaft powering said piston, said means comprising, a powered shaft journalled within the pump housing and adapted for rectilinear movement relative thereto, means for imparting rectilinear positioning movement to said shaft, an inner eccentric movably mounted on said shaft, helical means carried by said shaft for imparting arcuate movement to said inner eccentric in a first direction upon axial displacement of said shaft, an outer eccentric circumposed about said inner eccentric and having a circular peripheral surface for imparting reciprocal motion to the pump piston, additional helical means carried by said shaft for imparting arcuate movement to said outer eccentric in a direction opposite to said first direction of the inner eccentric upon axial displacement of said shaft, and means coupling said additional helical means to said outer eccentric and providing for lost motion therebetween during arcuate movement of the outer eccentric by said additional helical means with the center of said outer eccentric adjustably moving along a single plane containing the axis of the powered shaft with maximum eccentricity of the outer eccentric at all times occuring along said single plane and in a fixed coplanar relationship with the imaginary point on said powered shaft.
 2. Means for varying the stroke of a pump piston as claimed in claim 1 wherein said helical means includes axially spaced curvilinear grooves formed in and directed oppositely about said shaft and follower pins disposed within said grooves.
 3. Means for varying the stroke of a pump piston as claimed in claim 2 wherein the grooves in said shaft are of unlike curvature for imparting desired dissimilar arcuate movement in a simultaneous manner to both inner and outer eccentrics.
 4. Means for varying the stroke of a pump piston as claimed in claim 2 wherein said grooves are of like curvature, said coupling means including an arm of curved configuration adapted to provide varying degrees of lost motion between said additional helical means and the outer eccentric during adjustment of the latter. 